The AmSel Process Selective Separation of Americium from PUREX raffinate

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1 The AmSel Process Selective Separation of Americium from PUREX raffinate Christoph Wagner, Udo Müllich, Andreas Geist, Petra J. Panak KIT Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft

2 Introduction Partitioning and Transmutation: Strategy to reduce long term radiotoxicity and heat load of nuclear waste. Aim: separation of Pu and minor actinides (Np, Am and Cm) and transmuting them into short-lived or stable nuclides. Our goal: selective extraction of Am(III) from PUREX raffinate separation of Am(III) from Cm(III), Ln(III) & other fission products (FP) and corrosion products (CP) 2

3 Why separate americium from curium? Curium: no significant impact on long-term radiotoxicity or heat load of nuclear waste High neutron dose rates and decay heat complicate production of new nuclear fuel disposal in high active waste Separation of Am(III) should be performed early in the process PUREX Am Cm FP Ln Am(III)/(Cm(III) + Ln(III) + FP) sep n Pu U Np Cm + Ln + FP Am EXAm process already successfully tested Bollesteros, M.-J.; Calor, J.-N.; Costenoble, S.; Montuir, M.; Pacary, V.; Sorel, C.; Burdet, F.; Espinoux, D.; Hérès, X.; Eysseric, C., Procedia Chem. 2012, 7,

4 Strategy Co-extraction of Am(III), Cm(III) and Ln(III) Selective Am(III) stripping 4

5 Strategy Co-extraction of Am(III), Cm(III) and Ln(III) TODGA Extracts An(III) + Ln(III) from HNO 3 Rejects most non-ln fission products Rejects corrosion products Successfully used in DIAMEX and i-sanex processes 5

6 Strategy TODGA prefers Cm(III) over Am(III) SF Cm(III)/Am(III) = 1.6 Requirement for selective Am(III) stripping: Ligand has to prefer Am(III) over Cm(III) Well soluble in water / nitric acid BTBP prefers Am(III) over Cm(III) SF Am(III)/Cm(III) = 1.6 Water soluble BTBP? SF(TODGA) SF(BTBP) = 2.6? 6

7 Extraction experiments with TODGA and SO 3 -Ph-BTBP D(M(III)) Am(III) Am(III) Cm(III) Eu(III) SF Cm(III)/Am(III) SF [HNO 3 ] ini [mol/l] SF Cm(III)/Am(III) = SF Eu(III)/Am(III) 10-2 Aq. phase: 20 mm SO 3 -Ph-BTBP, Am(III)-241, Cm(III)-244, Eu(III)-152 (1 kbq/ml each) in HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 7

8 Extraction experiments with TODGA and SO 3 - Ph-BTBP D(M(III)) ,1 D(Am(III)) D(Eu(III)) D(La(III)) D(Ce(III)) D(Pr(III)) D(Nd(III)) D(Sm(III)) D(Eu(III)) D(Gd(III)) D(Am(III)) D(Cm(III)) 0,01 1E-3 1E [HNO 3 ] ini [mol/l] Aq. phase: 20 mm SO 3 -Ph-BTBP, Am(III)-241, Cm(III)-244, Eu(III)-152 (1 kbq/ml each) and 6 mg/l of each Ln(III), Y(III) and La(III) in HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 8

9 Extraction experiments with TODGA and SO 3 -Ph-BTBP D(Am(III)) 10 3 D(Eu(III)) D(Am(III)) D(Cm(III)) 10 3 D(M(III)) SF Cm(III)/Am(III) SF Cm(III)/Am(III) 10-1 slope = [SO 3 -Ph-BTBP] 10-1 Formation of 1:1 complex? TRLFS studies Aq. phase: SO 3 -Ph-BTBP, Am(III)-241, Cm(III)-244, Eu(III)-152 (1 kbq/ml each) in 0.51 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 9

10 Complexation of Cm(III) with SO 3 -Ph-BTBP Cm(III) emission spectra with increasing SO 3 -Ph-BTBP concentration in 0.5 M HNO nm nm nm c(aq-btbp) in mol/l E E E E E E E E E E E E E E E E E E E E E ,0 0,8 [Cm(solv)] nm nm nm [Cm(solv)] Wavelength (nm) [Cm(SO 3 -Ph-BTBP) 2 ] Wavelength (nm) only one complex species 0,6 0,4 0,2 [Cm(SO 3 -Ph-BTBP) 2 ] 5-0, [SO 3 -Ph-BTBP] [mol/l]

11 Complexation of Eu(III) with SO 3 -Ph-BTBP Eu(III) 7 F 4 band emission spectra with increasing SO 3 -Ph-BTBP concentration in 0.5 M HNO nm nm nm nm nm nm nm c(aq-btbp) in mol/l E E E E E E E E E E E E E E E E E E Wavelength (nm) 1,0 [Eu(SO 3 -Ph-BTBP) 2 ] 5- [Eu(SO 3 -Ph-BTBP)] - [Eu(solv)] [Eu(solv)] [Eu(SO 3 -Ph-BTBP) 2 ] 5-0, Wavelength (nm) 0,6 0,4 2 complex species formed, primarily 1:2 complex 0,2 0,0 [Eu(SO 3 -Ph-BTBP)] [SO 3 -Ph-BTBP] [mol/l]

12 Complexation of Cm(III) with SO 3 -Ph-BTBP 3+ +SO 3 -Ph-BTBP 4-3 -SO 3 -Ph-BTBP 4- -SO 3 -Ph-BTBP SO 3 -Ph-BTBP 4- logk 01 logk log([cm(so 3 -Ph-BTBP) 2 ]/[Cm 3+ (solv)]) Cm(III) complexation -6,0-5,6-5,2-4,8-4,4-4,0-3,6 log([so 3 -Ph-BTBP] free ) Slope log 02 log([eu(so 3 -Ph-BTBP) n ]/[Eu(SO 3 -Ph-BTBP) n-1 ]) Eu(III) complexation n = 2 slope n = 1 slope = ,8-4,4-4,0-3,6-3,2 log([so 3 -Ph-BTBP] free ) log 02 = 7.3 ± 0.3 log 02 = 5.4 ± 0.5 log 02 =

13 TRLFS with extraction experiments 2 phase extraction experiments containing Cm(III)/Eu(III) in the aq. Phase aq. phase extraction experiment [Cm(SO 3 -Ph-BTBP) 2 ]5- TRLFS spectrum aq. phase extraction experiement [Eu(SO 3 -Ph-BTBP) 2 ] 5- TRLFS spectrum Wavelength (nm) Wavelength (nm) SO 3 -Ph-BTBP forms 1:2 complexes in extraction experiments Aq. phase: 20 mm SO 3 -Ph-BTBP, Cm(III)-248 in 0.5 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 13

14 Complexation of Cm(III) at ph 3 TRLFS investigation of Cm(III) with SO 3 -Ph-BTP showed the formation of intermediate complexes studies with SO 3 -Ph-BTP were performed in water at ph 3 investigation of Cm(III) complexation with SO 3 -Ph-BTBP at ph 3 C. M. Ruff, U. Müllich, A. Geist and P. J. Panak, Dalton Trans., 2012, 41,

15 Complexation of Cm(III) at ph 3 Cm(III) emission spectra with increasing SO 3 -Ph-BTBP concentration in 10-3 M HClO Wavelength (nm) c(so 3 -Ph-BTBP) in mol/l E E E E E E E E E E E E E E E E E E-5 log 02 = 10.4 ± 0.4 (log (0.5 M HNO 3 ) = 7.3 ± 0.3) log([cm(aq-btbp) n ]/[Cm(aq-BTBP) n-1 ]) 1,0 0,8 0,6 0,4 0,2 0,0 0,0-0,2-0,4-0,6-0,8-1,0-1,2-1,4 calcd solvensspecies calcd [Cm(SO 3 -Ph-BTBP)] - calcd [Cm(SO 3 -Ph-BTBP) 2 ] 5- Solvensspezies [Cm(SO 3 -Ph-BTBP)] - [Cm(SO 3 -Ph-BTBP) 2 ] [SO 3 -Ph-BTBP] [mol/l] n = 1 slope n = 2 slope ,6-6,6-6,4-6,2-6,0-5,8-5,6-5,4 log[aq-btbp] free 15 large influence of solvent

16 Complexation of Cm(III) in different media c(so 3 -Ph-BTBP) in mol/l 0.5 M NaClO 4, ph M NaNO 0 3, ph E E E E E E E E E E E E E E E E-5 c(so 3 -Ph-BTBP) in mol/l E E E E E E E E E E E E E E Wavelength (nm) 0.5 M HClO c(so 3 -Ph-BTBP) in mol/l E E E E E E E E E E E E E E E E E E-4 Wavelength (nm) Wavelength (nm)

17 Influence of medium on conditional stability constant M(III) Solvens log 01 logk 12 log 02 Cm 10-3 M HClO ± ± ± 0.4 Cm 0.5 M HNO ± 0.3 Cm 0.5 M NaClO ± 0.3 Cm 0.5 M NaNO ± 0.3 Cm 0.5 M HClO ± 0.4 Large effect of medium on speciation and conditional stability constant 17

18 Influence of ionic strength ionic strength in mol/l 1.0 E E E E E E E E Cm-SO 3 -Ph-BTBP complexation with increasing ionic strength log logk 12 log Wavelength (nm) ionic strength in mol/l 1.0 E E E E E E E E cond. stability constant E-3 0,01 0,1 1 ionic strentgh (mol/l) Wavelength (nm) 18

19 Conclusion The SO 3 -Ph-BTBP/TODGA system shows good performance for the separation of Am(III)/Cm(III). The system does not require buffers, auxiliary ligands or salting out agents. SO 3 -Ph-BTBP forms 1:2 complexes during extraction. Formation of the same complexes in monophasic and biphasic experiments. The applied medium has a large effect on the speciation and the conditional stability constants of M(III)-SO 3 -Ph-BTBP complexes. 19

20 Outlook Extraction experiments at elevated temperatures. Investigation of SO 3 -Ph-BTBP loading with realistic Am(III) concentrations. Spectroscopic investigation of Am(III)-SO 3 -Ph-BTBP complexes. 20

Walschburger And all colleagues from INE Acknowledgements

21 Thank you for your attention Acknowledgements to: Prof. Dr. Geckeis The partitioning group Tanja Kisely and Cornelia Walschburger And all colleagues from INE Acknowledgements to the Commission of European Community for financial support 21

22 Complexation of Cm(III) in the org. phase TRLFS experiments with organic phase of extraction experiment org. phase extraction experiment [Cm(TODGA) 3 ](NO 3 ) 3 org. phase extraction experiment [Eu(TODGA) 3 ](NO 3 ) 3 TRLFS spectrum Wavelength (nm) Wavelength (nm) No evidence for the formation of mixed complexes sensitivity too low? Aq. phase: 20 mm SO 3 -Ph-BTP, Cm(III)-248 in 0.5 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80 22

23 Fluorimetric measurements with org. Phase 3,20 2,56 1,92 Idea: Utilizing the energy transfer from ligand to metal to selectively excite the Eu(III) in mixed complexes Emissionwavelength (nm) ,28 0, Excitationwavelength (nm) 23 Aq. phase: 20 mm SO 3 -Ph-BTP, 30 mm Eu(NO 3 ) 3 in 0.5 M HNO 3 Org. phase: 0.2 M TODGA + 5% vol. 1-octanol in Exxsol D80

24 Schematic flowsheet TODGA Extraction/ scrubbing Am(III) + Cm(III) + Ln(III) FP + CP TODGA Am(III) stripping Cm + Ln(III) Cm(III) + Ln(III) stripping HAR FP + CP Feed Am(III) + Cm(III) + Ln(III) + FP + CP Scrub sol n Product Am(III) Am(III) SO 3 -Ph-BTBP HAR Cm(III) + Ln(III) Cm(III) + Ln(III) Cm(III) + Ln(III) strip sol n 24

25 pk a value of SO 3 -Ph-BTBP 1,0 extinction ph 226 nm 305 nm 327 nm 319 nm wavelength [nm] pk a = 2.2 ± ,7 2,4 2,1 1, ,28 1,01 0,68 0,36-0,06-0,36 log( (erste protonierte Spezies)/ (unprotonierte Spezies)) 0,8 0,6 0,4 0,2 0, ,6 0,4 0,2 0,0-0,2-0,4-0,6-0,8 calcd unprotonated ligand calcd protonated ligand unprotonated ligand protonated ligand a(h + ) slope = ,0-3,2-3,0-2,8-2,6-2,4-2,2-2,0-1,8-1,6-1,4 log(a(h+)) 25

26 TRLFS Setup 26 Christoph Wagner A new system for the separation of americium from PUREX raffinate

27 Spectroscopic properties of Cm(III) weak ligand field strong ligand field - Identification und quantification of different species - Large effect of changes in first coordination sphere - Little effect of changes in second coordination sphere 27 Christoph Wagner A new system for the separation of americium from PUREX raffinate

28 Spectroscopic properties of Eu(III) wavelength (nm) Small shifts of the emission bands with changes in inner coordination sphere Characteristic splitting Information on the coordination structure and symmetry 28 Christoph Wagner A new system for the separation of americium from PUREX raffinate

Selective complexation of f-elements Partitioning & Transmutation

Selective complexation of f-elements Partitioning & Transmutation Antje Bremer, Andreas Geist, Petra J. Panak 1 KIT Universität des Landes Baden-Württemberg und nationales Forschungszentrum in der Helmholtz-Gemeinschaft